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<title>The WHILE keyword.</title>
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<center><h1>The WHILE keyword.</h1></center>
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The <b>while</b> keyword is related to <a href=do.html>do</a>
and <a href=for.html>for</a>. Its purpose is to repeatedly execute
a <a href="statements.html#blocks">block</a> of statements. Here is 
an example :

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        main()
        {
            int i=5;

            while(--i)
            {
                printf(" i is %d\n", i);
            }
        }
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The expression <b>i--</b> is evaluated and if its 
<a href="../CONCEPT/true_false.html">true</a> the statements in the 
<a href="statements.html#blocks">block</a> are executed. 
The loop continues until the expression is false (zero).
The result will look like this:

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                i is 4
                i is 3
                i is 2
                i is 1
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It is important to note that the statements 
on a <b>while</b> will not get executed if the first evaluation of the
expression is FALSE. If you do not want this to happen you may prefer
to use the <a href="do.html">do</a> statement.

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<p>
Now consider the next example.

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        main()
        {
            int i=5;

            while(--i);
            {
                printf(" i is %d\n", i);
            }
        }
</pre>
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The result will look like this:


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                i is 0
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<p>
This is because of the <b>;</b> on the end of the <b>while</b>
statement which means the <b>while</b> will loop (executing NULL statements)
until <b>i</b> is zero. Execution will then continue down the program 
(to the printf).
<p>

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<h2>Examples:</h2>

<img src="../../GRAPHICS/computer.gif" align=left alt="o">
<a href="../EXAMPLES/while.c">Basic <b>while</b></a>.
<br clear=left>

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<h2>See also:</h2>
<ul>
<li><a href="while.html">for</a> keyword.
<li><a href="do.html">do</a> keyword.
<li><a href="break.html">break</a> keyword.
<li><a href="continue.html">continue</a> keyword.
</ul>


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<address><a href="../../address.html">Martin Leslie</a> 
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